Low-temperature plasma-activated medium inhibited invasion and metastasis of melanoma cells via suppressing the Wnt/β-catenin pathway

Low-temperature plasma (LTP) has shown promising and potential applications in the field of biomedicine. The effects of the plasma-activated medium (PAM) inhibiting tumor cell invasion and metastasis have been verified, but the associated molecular mechanisms are poorly understood. The aim of this study was to identify the anti-invasion and antimetastasis effects and mechanism induced by PAM on B16 melanoma cells cultured in vitro. For this purpose, an atmospheric pressure plasma jet in helium was applied to generate PAM to treat B16 cells. Cell invasion and migration assays showed that PAM exerted an inhibitory effect on B16 cell invasion and migration in a time-dependent manner. Then, detection of the invasion- and metastasis-related proteins, including matrix metalloproteinase (MMP)-2, MMP-9, CD44, and E-cadherin, showed that their changes accorded with the invasion and metastasis of the PAM-treated B16 cells. Furthermore, the Wnt/beta-catenin pathway-related proteins in PAM-treated cells were measured, and the pathway was found to be suppressed by PAM. Finally, numerous specific reactive oxygen species (ROS) scavengers were applied to eliminate LTP-induced ROS in PAM, and it was revealed that H2O2 played a critical role in these processes. These findings demonstrated that PAM exerted anti-invasion and antimetastasis effects on B16 cells mainly by suppressing the Wnt/beta-catenin pathway, which consequently decreased the expressions of MMP-9, MMP-2, and CD44 via H2O2.